Masonry Magazine December 1994 Page. 25
Northridge
Earth Quake!
Reinforced Masonry Performs Well
by John Chrysler*
In the immediate aftermath of the 1994 Northridge Earthquake, masonry received considerable attention, some adverse. Some may think that the performance of masonry was inadequate, but the facts clearly state that masonry performed very well. It is a fact that not one life was lost due to masonry failures in this earthquake.
Immediately following the 6.8 magnitude earthquake, the news media reported the widespread building damage, which included an abundance of damaged brick chimneys and fallen property fence walls. These spectacular scenes grossly misrepresented the overall performance of masonry.
The property fence walls are not regulated by the permit and inspection process of the Uniform Building Code as long as the height does not exceed 6 feet. This may be considered a loophole in the Code, but people generally expect that these property fence walls will be constructed to withstand normal wind and seismic forces.
There was one 40 foot failure in the hundreds of miles of sound barrier walls along the Southern California freeways. There were very few masonry wall failures of public service facilities, such as hospitals, police stations and fire stations, electrical service facilities and in commercial construction. It is interesting that these successfully constructed walls are much taller that the 6 foot property fence walls.
Normally, minimum steel at 48" on center should be expected, with horizontal steel at the top of the wall. To be effective, the cells that contain the steel must be fully grouted. Additionally, the footings that support the property fence walls must be adequate to withstand not only the weight of the wall but also the overturning forces of wind and earthquakes. Generally, these provisions were not met causing wall failures.
*Director of Technical Services
Masonry Institute of America, Los Angeles, CA
4:31
January 17, 1994